Overview
The FAN6248LDMX is an advanced synchronous rectifier (SR) controller designed by onsemi, optimized for LLC resonant converter topology. This controller is part of the FAN6248 family, which includes several versions tailored for different operating frequencies and turn-off threshold voltages. The FAN6248LDMX is specifically designed to drive SR MOSFETs in high-efficiency power supplies, ensuring minimal external component requirements. It features two independent gate driver stages with adaptive parasitic inductance compensation, which maximizes efficiency by minimizing body diode conduction. The controller supports stable SR operation across the entire load range and includes advanced control algorithms for robust performance.
Key Specifications
| Parameter | Min | Typ | Max | Unit |
|---|---|---|---|---|
| VDD (Power Supply Input Pin Voltage) | -0.3 | 30 | V | |
| VD1, VD2 (Drain Sense Input Pin Voltage) | -1 | 100 | V | |
| VGATE1, VGATE2 (Gate Drive Output Pin Voltage) | -0.3 | 30 | V | |
| VS1, VS2 (Source Sense Input Pin Voltage) | -0.4 | 0.4 | V | |
| PD (Power Dissipation at TA = 25°C) | 0.625 | W | ||
| TJ (Junction Temperature) | 125 | °C | ||
| VDD_ON (Turn-On Threshold Voltage) | 4.0 | 4.2 | 4.4 | V |
| VDD_OFF (Turn-Off Threshold Voltage) | 4.0 | 4.2 | 4.4 | V |
| fMAX (Maximum Switching Frequency) | 700 kHz | |||
| fMIN (Minimum Switching Frequency) | 25 kHz | |||
| tON_MIN_UL (Minimum On-Time Upper Limit for LD version) | 3.2 | 4 | 4.8 | μs |
| VGATE_MAX (Gate Clamping Voltage) | 9 | 10.5 | 12 | V |
| VOH (Output Voltage High) | 7 | V | ||
| VOL (Output Voltage Low) | 1.5 | V |
Key Features
- Advanced Synchronous Rectification: Optimized for LLC resonant converter topology with minimal external components.
- Independent Gate Driver Stages: Two driver stages for driving SR MOSFETs with their own sensing inputs.
- Adaptive Parasitic Inductance Compensation: Minimizes body diode conduction, maximizing efficiency.
- Stable SR Operation: Advanced control algorithm ensures stable SR operation across the entire load range.
- Green Mode Operation: Disables SR operation at very light load conditions to minimize operating current.
- Light Load Detection: Detects light load conditions and adjusts dead time accordingly.
- Adaptive Dead Time Control: Compensates for induced offset voltage due to stray inductances.
- SR Turn-off Algorithm: Uses a combination of present and previous cycle information for robust SR operation.
Applications
- High-Efficiency Desktop and Server Power Supplies: Ideal for high-power computing applications.
- Networking and Telecom Power Supplies: Suitable for high-reliability communication systems.
- High Power LED Lighting: Enhances efficiency in LED lighting systems.
Q & A
- What is the primary function of the FAN6248LDMX?
The FAN6248LDMX is an advanced synchronous rectifier (SR) controller designed to drive SR MOSFETs in LLC resonant converter topology.
- What are the key features of the FAN6248LDMX?
Key features include advanced synchronous rectification, independent gate driver stages, adaptive parasitic inductance compensation, and stable SR operation across the entire load range.
- What is the maximum switching frequency of the FAN6248LDMX?
The maximum switching frequency is 700 kHz.
- How does the FAN6248LDMX handle light load conditions?
The controller includes a light load detection function that adjusts the dead time and enters green mode to minimize operating current at very light loads.
- What is the purpose of the adaptive dead time control in the FAN6248LDMX?
The adaptive dead time control compensates for induced offset voltage due to stray inductances, preventing premature SR gate turn-off.
- What are the typical applications of the FAN6248LDMX?
Typical applications include high-efficiency desktop and server power supplies, networking and telecom power supplies, and high power LED lighting.
- What is the maximum power dissipation of the FAN6248LDMX at 25°C?
The maximum power dissipation is 0.625 W.
- What is the junction temperature range for the FAN6248LDMX?
The junction temperature range is from -40°C to 125°C.
- How does the FAN6248LDMX ensure stable SR operation?
The controller uses an advanced control algorithm that ensures stable SR operation across the entire load range.
- What is the minimum on-time upper limit for the LD version of the FAN6248LDMX?
The minimum on-time upper limit for the LD version is 4.8 μs.
